【作者】 蒋观军；

【导师】 卢振洋； 黄鹏飞；

【作者基本信息】 北京工业大学 ， 机械电子工程， 2006， 硕士

【摘要】 变极性脉冲MIG焊是一种新的焊接工艺方法,其综合了DCEP脉冲MIG焊熔深较大、可以减少焊缝的熔合不良、电弧稳定性好和DCEN MIG焊焊缝熔深浅、焊丝熔化速度较快的特点,减小了焊缝的熔深,增加了焊丝的熔化速度,是一种适合于薄板铝合金焊接的新方法。研究薄板铝合金变极性脉冲MIG焊接技术,更有效地控制焊接电流、电压输出和熔滴过渡过程,提高焊接过程的稳定性、提高焊接速度,对于提高焊接效率和焊接产品质量具有重要的意义。本课题是“变极性脉冲MIG焊设备及焊接稳定性研究”课题的一部分,主要针对变极性脉冲MIG焊设备完成辅助控制电路设计。主要包括:数字化的人机交互系统设计;送丝稳定、动态性能良好的送丝调速系统。首先,人机交互系统选用AT89S8252为核心控制芯片,选用具有串行总线接口的SD7218A键盘/显示芯片完成了数字化人机交互系统软、硬件设计;采用RS-485总线实现主控系统和人机交互系统的数据交互;系统采用数字编码器和键盘配合的方式实现焊接参数的选择和设定,同时还具有最优参数存储、调用等功能。对研制的人机交互系统进行了抗高频干扰试验,证明具有良好的抗干扰性能。其次,本文用采样速度均方差值作为衡量送丝系统的动态稳定性指标,采用LabVIEW软件设计了送丝机性能评估软件,利用该软件不但可以对送丝调速系统做出评价,还可以指导调速系统的设计。再次,从控制论的角度对转速负反馈、电压负反馈、电压负反馈配合电流正反馈等三种转速调节方式进行了分析论述,采用电枢电压负反馈配合电流正反馈方式设计了送丝机调速控制系统,并采用送丝机性能评估软件对调速系统进行了优化。设计了与主控系统的接口隔离电路,采用线性光耦对模拟信号进行隔离,普通光耦对数字信号进行隔离。最后,对本文设计的送丝机调速系统与NBC-350焊机的调速系统进行了对比试验,试验证明本文设计的调速控制系统具有良好的动态稳定性和良好的控制精度。更多还原

【Abstract】 The variable polarity pulsed MIG is a new welding technology. It has the predominance of DCEP MIG and DCEN MIG. The DCEP MIG has the characteristic of deeper penetration which can reduce defective fusion and good arc stabilization. The DCEN MIG has the characteristic of shallow penetration of welding seam, and the welding wire has a high melting speed. So the variable polarity pulsed MIG is a new technology for the welding of aluminium alloy sheet.It has important significance to study the welding technology of variable polarity pulsed MIG for high efficiency weding and good quality of welding products. We should control the welding current, output voltage and the process of melting drop more effectively. The paper is s sub-topic of the research of variable polarity pulsed MIG welding device and its welding stabilization. The main content is design of digital man-machine interface system, a speed regulating system of good stabilization and dynamic performance; software for appraising the performance of wire feeder.The first, a digital man-machine interface system using AT89S8252 singlechip is designed. The system uses SD7218A keyboard/display chip with serial bus interface. The welding parameters can be seleted and regulated easily with the cooperation of digital encoder and keystoke. At the same time the system has the function of storage and call of optimum parameters. The man-machine interface system communicates with the master system using RS-485 bus. Aimming at the man-machine interface system, we have done high frequency anti-interference experiment, it proves that the system has good performance of anti-interference.The second, we adopt the mean-squared deviation of speed as the index of dynamic stability and design an appraisal software of the performance of wire feeder. The software can not only appraise the performance of wire feeder but direct the design of speed regulating system.The third, the paper analyses and expatiates three mode of speed regulating which are speed negative feedback, voltage negative feedback and voltage negative feedback plus cuttent positive feedback and designs a speed regulating control system adopting the mode of voltage negative feedback plus cuttent positive feedback. At the same time we optimize the speed regulating system using the appraisal software of the performance of wire feeder. Finally designs the interface cirvuit with the master control system. The analog singal is isolated by linear optical isolator and the digital signal is isolated by common optical isolator.Finally, a comparison experiment is performed between the speed regulating system this paper designed and the speed regulating system of NBC-350 welding power source. The result indicates that the system this paper designed has good dynamic stability and control accuracy.更多还原